


Lazy blue

by silverryu25



Category: Undertale (Video Game)
Genre: But mostly fluff, Dorks in Love, Fluff, M/M, Mating Dance, No Smut, Sans (Undertale) / Sans (Underfell) - Freeform, Sans (underfell)/Sans (undertale) - Freeform, Sans/Sans (Undertale) - Freeform, Sanscest - Freeform, Underfell Sans/ Undertale Sans - Freeform, Undertale Sans / Underfell Sans - Freeform, for flavor, kustard - Freeform, mating is marriage here, mermaid Red - Freeform, mermaid sans, mermaid skeletons, sprinkled with some light angst, why do my kustard dorks never talk it out
Language: English
Status: Completed
Published: 2021-02-07
Updated: 2021-02-07
Packaged: 2021-03-12 23:14:48
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 3,307
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/29268561
Author URL: https://archiveofourown.org/users/silverryu25/pseuds/silverryu25
Summary: Sans is a lazy little mermaid skele that liked taking naps and eating and nothing else… for most of his life. But now he found something new to love, he just had to make sure he caught it.
Relationships: Kustard, Sans (Undertale) / Sans (Underfell), Sans/Sans (Undertale), Underfell Sans/ Undertale Sans, Undertale Sans / Underfell Sans, sans (underfell)/sans (undertale), sanscest
Comments: 23
Kudos: 83





	Lazy blue

**Author's Note:**

  * For [Fuzzyz_202](https://archiveofourown.org/users/Fuzzyz_202/gifts).



> This work was inspired by the [amazing and gorgeous art](https://020fuzyzz.tumblr.com/post/640826941782507520/click-on-image-for-better-quality-drew-this) made by Fuzzyz_202 (020fuzyzz on tumblr) (≧◡≦)♥
> 
> The moment I saw the art all I could think of was Sans and Red dancing and Sansy showing off that pretty tail of his! So this little fic was born :D
> 
> I hope you enjoy the mer dorks X3

The day was warm and sunny, sunlight glittering gently above his head as Sans sprawled on a nice soft sandy spot on the sea floor.

This was his favourite sunning spot, close to his den but far enough from anyone else to make it nice and quiet. So he usually spent most of his time here when he wasn’t foraging for food or telling jokes in the community cave. It wasn’t that he didn’t like the company of others, and he could fall asleep practically anywhere, but this spot was the warmest and softest he ever found and sometimes lunch tended to walk up to him if he was still enough.

The perfect napping spot.

Normally, he wouldn’t even consider leaving here on such a perfect sunny day, but today was different. Today was important. Because, for the first time in Sans’ life, he was going to join in the mating dance. The yearly ritual his little school did that served as a bonding ceremony for mer’s that wanted to commit to a lifetime mate.

Sometimes, mer’s that hadn’t picked a mate beforehand joined the dance in hopes of finding someone that would resonate with their soul, but mostly everyone was already paired up, having chosen beforehand who they want to bond with. That’s why Sans had never been to one of the dances. And he was sure he never would.

He knew everyone in their school, it wasn’t a very big one and he was an easy laidback type of guy that everyone liked to talk to. But he never really felt attracted or interested in any of the mer’s he knew. He even visited a nearby school, only a few days swim away, as part of creating an alliance for the mutual benefit of both groups, but he never found anyone interesting there either.

It was like his soul wasn’t built for bonding.

At first, it had made him sad that he would never be able to have what he saw the other mer’s sharing. That deep connection and the satisfaction of having someone to share his everything with. But he had his brother and the others in the school, and eventually it was enough. He made himself accept that sometimes life just worked that way and he could find other ways to fill in that hole in his soul.

He was happy. He could take a lot of naps and eat as much as he could gather. He always had a full belly, enough to earn him some chub even, which was rare. And he helped around the school when he felt a little lonely, taking care of the guppies or telling jokes to the mer’s that gathered in the community cave. He had it all. And he was happy.

Until something changed.

A new mer arrived, carrying another, severely wounded one. They were brothers and they were very different.

Unlike Sans and the rest of his school, that looked soft and lived pretty peaceful lives, these mer’s looked like they went through hell and back. Covered in scars and nicks, they were battle hardened. Their magic was a taunting red daring their enemies to try and attack, declaring that none would survive the attempt. And Sans could believe it.

The wounded mer looked to be in a bad state, yet he was up swimming around in a matter of a few days, even though the healer told him to rest. But he was stubborn and he was loud and he scared the healer off. Yet he recovered like it was nothing. Sans was pretty impressed by that, even if he couldn’t really understand how someone would refuse a nap? Especially a prescribed one.

But the nap-hating mer wasn’t what drew Sans’ attention to the pair, though he did love to annoy him with puns and jokes. His reactions were almost better than Papy’s… as long as he dogged the bone attacks, heh.

The other, apparently older brother, was the one that piqued Sans’ interest. 

At first, Sans just wanted to see the new mer’s and learn some news or new jokes. When he learned that the older mer’s name was Red, like his tail, he almost laughed his fins off at the pun potential, so he  _ had _ to see him and use some of his puns right away. He expected annoyance, maybe a chuckle or two, but what he didn’t expect was a worthy opponent.

Red almost out-punned him!

Sans was shocked! He had to dig deep into his pun game to preserve some of his dignity as the main jokester of his school. But soon enough that shock grew into something more. Fun. He was having so much fun. Red was hilarious and he made Sans’ bones rattle with how hard he was trying not to laugh. He hadn’t had this much of a good time in… ever?

And it only got better. Red  _ loved _ naps. Sans would say almost more than him, which was very surprising to say the least. Especially since Red seemed to always be tired. Sans eventually managed to find out why and he wasn’t sure if he regretted it. Red’s life had been hard before he stumbled to Sans’ school, the scars more than enough evidence to that. Edge, Red’s brother, and he had been living alone in a more dangerous part of the ocean. Their lives were in danger almost constantly and sleep came hard to Red, nightmares plaguing the nights and waking him up constantly. Even now, when he was finally safe, Red had a hard time getting enough rest. When Sans learned all this, he decided to do something he never thought he would.

He shared his favourite napping spot with Red.

It was his most important secret and now Red knew it too. Sans was blushing the whole swim to the spot, hiding it from Red by swimming ahead and keeping his head turned forward. He wasn’t sure why doing that made him so excited, and why he really hoped Red would like the spot. His soul was beating hard and he swam faster than anyone knew he could. When they arrived and Sans saw Red frowning at the spot, his soul sank for a moment, but it didn’t last long as Red grabbed him and cuddled him close in the spot, saying it was now perfect.

Sans’ soul beat a mile a minute that day.

He quickly realized that what he was feeling for Red was something he never thought he would experience… he was in love. His soul wanted to have Red there forever. To bond and connect and share his everything. He wasn’t sure if Red felt the same but… today was his chance to find out.

The mating dance.

It would start soon and Sans was starting to feel nervous. If Red didn’t show up to it, then Sans would have to give up. His soul felt like it would break if that happened, but he would never force Red to be with him. So he made sure Red knew what today meant, leaving hints at how important the day was and that he would probably join this year. Red didn’t seem too interested, quickly changing the topic and looking away from Sans, but Sans still hoped. He hoped Red would be there… for him.

With a soft sigh, Sans gathered what courage he had in his soul and stretched. It was time to swim to the place where the community cave was, the dance would be happening outside the entrance so everyone participating could have enough space. He swam there slowly, nervousness building up in his belly the closer he got. He turned around and saw his tail was a bit dull, reflecting his emotions, so he tried to cheer up. But it didn’t work, it only made his anxiety worse and the tail dimmer. He gave up, hoping that it would be okay once he saw Red there.  _ If _ he saw Red there.

He came in pretty early. The dance would last the whole day, though everyone tended to gather pretty early for it, the excitement driving them to it. He saw a lot of mer’s he already knew would bond this year and even some that surprised him, but he was the biggest surprise to everyone as he swam past them, barely returning their greetings. Sans knew it was impolite and would usually take his time to greet each mer and maybe throw a joke or two. But his mind was full of only one thing, ‘ _ find Red’ _ and he didn’t have time for distractions.

So he swam around, looking for any hint of red in the water around him. But he couldn’t see any. Red… didn’t come?

Sans could feel his soul constrict painfully as the thought sank in. He watched the other mer’s pair up, starting their dances, looking happy as they laughed and giggled and held hands while they swam together. He saw this scene a few times before when his curiosity got the better of him and he decided to peek, even though he never felt the need to join. But it never felt like this. Sure, he was curious what it would be like to do the dance with someone, but he wasn’t really sad that he would never find out. Now?

His soul felt like it was going to break apart.

If Sans had known how much falling in love could hurt, he never would have let it happen. He could feel his tail sag, losing even more of its glow as he sunk to the ocean floor. What was the use in trying to swim up when there was no one to swim with? He stayed there, waiting, as the dancers slowly finished their bonding and started swimming away. The mating dance would soon be over, but Sans still stayed and patiently waited. When only a few were left, he realized that it was done and that he should probably just go to his napping spot… or maybe find a different one now? He didn’t want to find Red there. He couldn’t face him today.

Just as he was about to swim away, keeping low so he wouldn’t disturb the remaining dancers, he caught a flash of something colourful in the corner of his socket. Lazily, he turned his head not expecting anything. He watched as the tiny spot grew and he could tell it was something red swimming fast towards the cave entrance. Sans stopped and sank back down to the ocean floor, watching and waiting, curiosity keeping him in place, as the spot grew into… Red.

Sans stared at him, feeling conflicted. He wasn’t sure if Red was there for him or not. He was very late, the mating dance was almost over, so why was he here now?

Red swam around, frantically looking everywhere, but it looked like he didn’t find what he was searching for. He looked angry and frustrated as he swam back and forth, clutching something in one of his hands and keeping it close to his chest. The blue mer looked on, unsure if he should swim up to him. Steeling himself, hoping this wouldn’t end in another disappointment, Sans decided to risk it. He swam up a bit, trying to get Red to notice him, unsure if he would with his tail so dull.

It took only a moment for Red to spot him, his hunting instincts probably making it easier to notice any movement nearby. Sans watched as Red zeroed in on his position and swam as fast as he could. He barely managed to stop himself from barreling into Sans when he was close enough, the pressure from his swim making Sans swim harder to keep his place.

When Sans was sure he wouldn’t be blown away, he looked up at Red and saw he was blushing a deep crimson. Sans tilted his head, unsure what was wrong. He could see Red was breathing hard too, which might have been from the swim, but Sans never really saw the sharp-toothed mer winded from swimming. Was Red sick? Is that why he didn’t come before?

Without a word, Red took a deep breath, clutching something in both hands as he thrust them at Sans, his blush deepening. Sans looked at the tightly closed fists confusedly, unsure what he was supposed to do. Wrestle Red for what he was holding? Or…

Before he managed to ask, Red opened both palms revealing a pearl. It was huge, a lot bigger than any Sans ever saw. And it was blue and indigo and cobalt and azure and so many more shades of blue, Sans couldn’t even name them. It looked like the colours danced inside the pearl instead of on the top. It was beautiful.

“red?” Sans asked hesitantly. “what’s this?”

Red looked up at Sans, startled, as if Sans had asked something completely unexpected. He studied Sans’ face, searching for something, but it looked like he didn’t find it and he relaxed.

“ya really don’ know?” Red asked and Sans shook his head no. He literally hadn’t seen something like this in his whole life. Red chuckled nervously and said “yer matin’ gift. dat is, if ya want me?”

_ ‘mating gift?’ _ Sans’ sockets spread wide as he stared at the bigger mer. What the heck was a mating gift? He knew of a mating dance, but never of a mating gift. His face must have shown his confusion cause Red quickly explained.

“i had ta go pretty far ta get it, i ain’t late right?” He sounded nervous, maybe even a bit panicked. “wanted it ta be somethin’ pretty… like ya. or yer tail. it has so many pretty shades of blue, bright when yer tellin’ puns, dark when i told ya ‘bout my nightmares, and many in between. an’ i wanted ta get somethin’ dat was at least half as pretty as ya… do ya like it?”

Sans could feel his face burn more and more as Red talked. He thought all that about Sans’ tail? He had been watching it that closely? To notice all the different shades it could take. He took a quick look down, noticing that his tail had started shining a brilliant blight blue, the colour of the sunny sky he loved to gaze at so much from his little sunning spot.

“yea,” Red said, making Sans look up and notice he was also looking at Sans’ tail. “beautiful like dat.”

Sans could feel his face was probably blushing hard enough that it looked as blue as his tail did. Red didn’t usually say such sweet things, and judging by the crimson blush slowly spreading on his skull, he wasn’t used to them either. Suddenly, Sans realized that he didn’t get Red anything. No gift, especially nothing as amazing as that…

“but…” Sans lovered his head as he hesitantly whispered out, making Red lean closer so he would catch it. “i don’t have nothing for you. the mating dance is just that, a dance. there are no gifts, so i don’t… i don’t have anything to give you…”

“oh…” Red breathed out, making Sans look back up at him. “den i messed up? fuck. sorry sweetheart, i didn’ know. i hear from another school dat ya gotta give a good gift ta da one ya want ta be yer mate. didn’ know it was just a dance? fuck, ya probably wouldn’ even want a stupid mer like me. i know almost nothin’ bout living in a school and i-”

Red’s words were stopped by a kiss as Sans practically jumped into his arms and connected their teeth. The kiss wasn’t very pleasant, the speed of it making it almost painful, but it stopped Red’s mind from spiralling down and made him blush even deeper. He grabbed Sans around his waist, as he kept the pearl clutched in his claws and swam to keep them both in place, and deepened the kiss, making Sans moan a little as Red took control. They continued for a few moments, when Red pulled back.

“does dat mean yes?” Red asked, a little out of breath.

“yes!!” Sans breathlessly shouted as he bobbed his head in confirmation. It was more than a yes in his mind. It was so much more than he would have ever hoped for.

Red whooped as he got the positive answer and spun them around, making sure he kept a tight grip on Sans. The smaller mer just giggled at the bigger’s antics, but the movement reminded him of something important. They still had to do the dance to make their mating official in the school.

“red?” He drew Red’s attention by tapping him on his chest. “we have to do the dance, remember? so everyone knows we are mates now. that’s how we do it here. so will you take the dance as my gift to you?”

Red looked a bit surprised, but nodded his head and let Sans go, unsure how this was supposed to be done. Sans extended a hand and took the pearl from Red, it would get in the way for the dance so he quickly swam to the ocean floor and put it in a safe spot. When he was sure he could find it again, he swam back up to Red and stopped a few feet away from him.

“ready?” Sans asked, a grin spreading on his skull as he focused on Red.

“uhhhh... yea’?” Red hesitatingly said, making Sans frown a bit.

“what’s wrong?” He asked, unsure if Red was changing his mind.

“... i… don’t know how ta dance,” Red admitted after a few moments, a hand scratching the back of his neck as he looked away, obviously ashamed of the fact.

“oh, is that all?” Sans asked, giggling a little and startling Red into looking back up at him. “don’t worry bigbone, i’m gonna do the dancing, you just follow, ok?”

Red hesitated for only a second, then gave Sans a determined nod, making Sans smile even brighter. He was sure Red would know what to do once he started, so he didn’t hesitate.

Sans spread his arms and somersaulted in front of Red, getting closer to him and pulling him with him. Red got the hint and started swimming with Sans, the smaller mer’s back to the ocean floor. They swam like that for a bit, then Sans led them into a twirl and a loop. They continued twisting and turning, doing loops and spirals up towards the surface, then back down towards the ocean floor. They were both laughing as they followed each other, letting their bodies synchronize to a song only their souls could hear.

Suddenly, Sans let go of Red and turned around, his back and tail arching in opposite directions as all his fins flared, showing off his whole tail that was shining brightly with his excitement and happiness, as if showing everything he was and was willing to give to his mate. Red could only stare, a soft smile on his sharp teeth as he admired the little mer that was offering him so much. Sans’ smile spread wide as he blushed, feeling his soul reach out to Red’s.

Red grabbed Sans and turned him to face him, their ribs connecting to get their souls as close as possible. Sans leaned up at the same moment Red leaned down. Their second kiss was a lot gentler and lasted longer as they explored each other completely.

They both felt the moment their souls bound to each other, sharing their everything, connecting them forever.

They continued to dance long after, neither wanting to break the spell, as the warm sunlight shone down on them, making their tails shine together brightly in the sunbeams.

**Author's Note:**

> Tada! See all fluff! 8D  
> The angst is just a little seasoning UwU
> 
> The whole idea behind the mating dance in Sans' school is that it represents a bonding/marriage ceremony where mers show who they have decided to mate/bond with :3  
> So yes, Sans and Red are married now! Woho! XD
> 
> Red wasn't aware what exactly he was supposed to do for the mating dance because he and Edge had lived alone for a loooooong time. So any knowledge he had was what he managed to gather while meeting other mers... that never took the two in ;w;  
> But now Red and Edge have a forever home where they will be safe and happy and well taken care off X3
> 
> I hope you enjoyed this little story (≧◡≦)♥


End file.
